Conventional interferometers can be used for a variety of purposes in the fields of astronomy, fiber optics, engineering metrology, optical metrology, oceanography, seismology, spectroscopy, quantum mechanics, nuclear and particle physics, plasma physics, remote sensing, biomolecular interactions, surface profiling, microfluidics, mechanical stress/strain measurement, velocimetry, and optometry. In operation, interferometers utilize two beams that have propagated along different paths to produce an interference pattern that is attributable to optical path differences.
Interferometers can be characterized as double-path interferometers or common path interferometers. In double-path interferometers, a reference beam and a sample beam travel along divergent paths. Examples of double-path interferometers include the Michelson interferometer, the Twyman-Green interferometer, and the Mach-Zehnder interferometer.
In common-path interferometers, the reference beam and sample beam travel along the same path. Examples of common-path interferometers include the Sagnac interferometer, the fibre optic gyroscope, the point diffraction interferometer, the shearing interferometer, the air wedge shearing interferometer, the Zernike phase contrast microscope, Fresnel's biprism, the zero-area Sagnac, and the scatterplate interferometer.
Interferometers can be characterized as wavefront splitting interferometers or amplitude splitting interferometers. Wavefront splitting interferometers divide a light wavefront emerging from a point or a narrow slit. The two parts of the wavefront to travel through different paths and are recombined. Examples of wavefront splitting interferometers include Young's interference experiment, Lloyd's mirror, the Fresnel biprism, the Billet Bi-Lens, and the Rayleigh interferometer.
Amplitude splitting interferometers use a partial reflector to divide the amplitude of the incident wave into separate beams which are separated and recombined. Examples of amplitude splitting interferometers include the Michelson interferometer, the Twyman-Green interferometer, the Mach-Zehnder interferometer, the Fizeau interferometer, the Fabry-Pérot interferometer, the laser unequal path interferometer, and the Linnik interferometer.
Other examples of interferometers include the Gires-Tournois interferometer, the Jasmin interferometer, the Lummer-Gehrcke interferometers, the Mirau interferometer, the Rayleigh interferometer, the n-slit interferometer, and the self-feedback/mixing/backscatter interferomer.